A wild variety of bitter melon Momordica charantia L. (Cucurbitaceae) has been used in bush medicine of Trinidad and Tobago for treatment of diabetes, inflammations and cancer. Despite many studies regarding the cultivated bitter melon, the wild variety has been poorly investigated. This study evaluates the biological activities of the ethanol/water extract of aerial parts and correlates these activities with the presence of phenolic compounds. The extract exhibited antioxidant activity in the four assays (DPPH, reducing power, B-carotene bleaching and TBARS). The key role of oxidative stress in inflammation and tumorigenesis was supported by the results of anti-inflammatory (inhibition of nitric oxide production) and cytotoxicity (human tumor cell lines, namely HeLa, HepG2, MCF-7, and NCI-H460) assays. In contrast, no toxicity was observed in non-tumor cells. In the antibacterial screening, clinical resistant isolates were significantly affected (MIC50 = 10–0.625 microg/mL), being Listeria monocytogenes the most susceptible. Three phenolic acids and eleven flavonol glycosides derivatives were identified, quercetin-3-O-pentosylhexoside being the most abundant.